Acrylate-based sulfur scavenging agents for use in oilfield operations

ABSTRACT

Composition for the removal or inactivation of hydrogen sulfide or soluble sulfide ion other species comprising ionizable sulfur (e.g., mercaptans, thiols, etc.) using compositions containing acrylate and/or derivatives thereof are provided. Methods for the removal or inactivation of hydrogen sulfide or other sulfur species in oilfield sites and other related applications using compositions containing acrylate and/or derivatives thereof are provided.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a U.S. National Stage Application ofInternational Application No. PCT/US2014/072070 filed Dec. 23, 2014,which is incorporated herein by reference in its entirety for allpurposes.

BACKGROUND

The present disclosure of this application relates to the removal orinactivation of hydrogen sulfide or other species comprising ionizablesulfur (e.g., mercaptans, thiols, etc.) which may be encountered inwells which penetrate subterranean formations such as oil wells, gaswells and the like. Fluids in sewage systems, fluids produced from wellsand make-up fluids also frequently contain hydrogen sulfide. Hydrogensulfide gas is toxic with a density heavier than air, and thereforeremoval or inactivation of this sulfide ion is necessary to preventpoisoning of surrounding personnel and contamination of the area.Moreover, hydrogen sulfide gas is highly corrosive to the pipeline andequipment used in the operation of an oil well. Therefore, removinghydrogen sulfide from produced fluid (i.e., oil and water) and gas isnecessary for the safe production of oil.

Drilling a well in a hydrocarbon bearing subterranean formation for theproduction of hydrocarbons from said formation typically involves use ofa drilling apparatus and drilling fluid. The drilling apparatus usuallycomprises a bit mounted on a string of hollow steel pipe. This hollowpipe is often used to rotate the bit to enable the bit to cut into theformation. The hollow pipe also acts as a conduit for the drilling fluidto be pumped down to the bottom of the hole, from where it rises to thesurface via the annulus between the drill string and the borehole wall.The drilling fluid has many functions, one of the most important ofwhich is to convey the cuttings from the bit downhole up to the surfaceof the well.

In drilling some subterranean formations, and often particularly thosebearing oil or gas, hydrogen sulfide accumulations are frequentlyencountered. The drilling fluid brings the hydrogen sulfide to thesurface. Such sulfide in the drilling fluid is problematic because itcan corrode the steel in the drilling apparatus and may be liberatedinto the atmosphere as toxic sulfide gas at the well surface. Generally,to protect the health of those working with the drilling fluid and thoseat the surface of the well, conditions should be maintained to ensurethat the concentration of hydrogen sulfide above the fluid, emitted dueto the partial pressure of the gas, is less than about 15 ppm.

Triazine-based hydrogen sulfide scavengers have been commonly used inthe the oil and gas industry, but triazine can increase pH values ofproduced water and cause scale problems. Moreover, triazine-basedscavengers contain nitrogen, which normally causes problems downstreamsuch as corrosion and damage to refining catalysts. Nitrogen-freescavengers such as formaldehyde, glyoxal, and acrolein have their ownproblems such as toxicity, corrosivity, and safety issues, which maycreate added difficulties for transportation, storage, and operation.

BRIEF DESCRIPTION OF THE FIGURES

These drawings illustrate certain aspects of some of the embodiments ofthe present disclosure, and should not be used to limit or define thedisclosure.

FIGS. 1 and 2 are diagrams illustrating the chemical structure of sulfurscavenging additives according to certain embodiments of the presentdisclosure.

FIG. 3 is a diagram illustrating a closed tank system used to applycertain embodiments of the sulfur scavenging additives of the presentdisclosure.

FIG. 4 is a diagram illustrating an injection system that may be used inaccordance with certain embodiments of the present disclosure.

While embodiments of this disclosure have been depicted and describedand are defined by reference to example embodiments of the disclosure,such references do not imply a limitation on the disclosure, and no suchlimitation is to be inferred. The subject matter disclosed is capable ofconsiderable modification, alteration, and equivalents in form andfunction, as will occur to those skilled in the pertinent art and havingthe benefit of this disclosure. The depicted and described embodimentsof this disclosure are examples only, and not exhaustive of the scope ofthe disclosure.

DETAILED DESCRIPTION

Illustrative embodiments of the present disclosure are described indetail herein. In the interest of clarity, not all features of an actualimplementation may be described in this specification. It will of coursebe appreciated that in the development of any such actual embodiment,numerous implementation-specific decisions may be made to achieve thespecific implementation goals, which may vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthe present disclosure.

The present disclosure of this application relates to the removal orinactivation of hydrogen sulfide or other species comprising ionizablesulfur using compositions containing acrylate and related compounds.More specifically, the present disclosure provides acrylate-basedcompounds for use as a sulfur scavenger in various operations. Incertain embodiments, the acrylate-based additive may interact with oneor more sulfur species to reduce the amount of or inactivate (i.e.,render the sulfur atoms in the sulfur species non-ionizable) at least aportion of the sulfur species present,

The sulfur scavenging additives of the present disclosure may compriseany acrylate-based compound known in the art. Methyl acrylate (IUPACname 2-methylpropenoic acid) is an example of one embodiment of theacrylate used in accordance with the disclosed subject matter. Theacrylate-based additives of the present disclosure may be less reactivethan certain conventional sulfide scavengers (such as acrolein), which,in certain embodiments, may make it less volatile, less toxic, easier tohandle, and more stable to store for periods of time than acrolein. Incertain embodiments, the acrylate-based additives of the presentdisclosure may cause less corrosion and/or form less scale in their useunder certain conditions. Also, acrylate's lower reactivity may makeacrylate more suitable for combining with other additives.

In certain embodiments, the additives may include a compound of thegeneral formula:

where R₁ represents any atom or functional group that can increase theactivity of the adjacent double bond, such as a hydrogen atom, alkylgroups, alkene groups, alkyne groups (any of which may be substituted,unsubstituted, linear, branched, cyclic, or acyclic), and anycombination or derivative thereof; and R₂ may be any hydrocarbon chainof any length and/or structure (including substituted, unsubstituted,linear, branched, cyclic, or acyclic chains). For example, in someembodiments, R₁ may comprise a C1 to C20 carbon chain of any of theaforementioned structures comprising an ester group, an ether group, acarbonyl group, a carbonyl amide group, a urea group, a urethane group,or any combination thereof. In certain embodiments R₂ may comprise a C1to C20 carbon chain of any of the aforementioned structures. In certainembodiments, the additive of the present disclosure may include acombination of different compounds having this formula.

The treatment fluids comprising additives of the present disclosure maybe hydrophobic, hydrophilic, or mixtures thereof, and may also include asolvent. The solvent may be an aromatic solvent, such as Aromatic 100,Aromatic 150, kerosene, diesel, or mixtures thereof. The concentrationof the solvent within the treatment fluid may be from about 1 to about99 wt %. The concentration of the compound within the treatment fluidmay be from about 1 to about 99 wt % of the treatment fluid. Thetreatment fluid may also include a corrosion inhibitor, a dehazer,and/or a conductivity improver.

As used herein, the term “acrylate” and “acrylate-based additive”includes all compounds containing the acrylate ion (CH2=CHCOO—), theirsalts and esters, as well as all derivatives thereof that are formed bysubstituting one or more H atom of the acrylate molecule with any Rgroups. For example, FIG. 1 shows methyl acrylate, which may be used inaccordance with certain embodiments of the present disclosure. Inaddition, acrylate derivatives can also be used in accordance with thepresent disclosure. FIG. 2 shows a generic acrylate derivative, whereinR₁ represents any functional group that can increase the activity of theadjacent double bond and R₂ represents a carbon chain of any length,including linear or branched chains. Moreover, the H atoms shown inFIGS. 1 and 2 can be replaced with R groups (i.e., side chains). Any Rgroup substitution is acceptable. In certain embodiments, larger, morecomplicated R groups may result in decreased reactivity of the sulfurscavenger. In addition, certain embodiments include sulfur scavengingfunctionalities in the R groups such as acrylonitrile.

In accordance with certain embodiments, a variety of suitable carrierfluids may be used to deliver the acrylate. Acrylate is typically oilsoluble, and therefore, oil-based carrier fluids can be used in certainembodiments. However, in certain embodiments, acrylate compositions usedaccording to the present disclosure may be used in aqueous fluids (e.g.,aqueous liquids) as well. In certain embodiments, the concentration ofacrylate used in the carrier fluid (or any fluid into which the acrylateis introduced) may be from about 0.5% to about 15% by weight of thefluid. At high temperatures, concentrations in a different range may beused, among other reasons, for example, to avoid polymerization of theacrylate monomers. In certain embodiments, the acrylate-based additivesof the present disclosure may be used at a neutral to slightly basic pH,among other reasons, because scale forms a higher pH and lower pH leadsto acidic corrosion. However, a slightly acidic pH (e.g., around 5) isalso suitable, though it may result in a slower reaction. In certainembodiments, temperature of the reaction may be 100° F. or higher,although other suitable temperatures may be used depending on thedesired rate of reaction.

In certain embodiments, acrylate or related compounds may be employed ina closed system to avoid exposure to the surrounding environment andpersonnel. To avoid exposure of acrylate or related compounds to theenvironment or personnel, certain embodiments may employ a closed tanksystem such as shown in FIG. 3. In certain embodiments, the apparatusillustrated in FIG. 3 may include a commercially available GPSreceiver/transmitter that has the capability to process 4-20 mA datasignals. An example of the type of GPS receiver/transmitter which may beused is a unit produced by Satamatics Ltd. (Model TAM210-Inmarsat D+Transreceiver).

In certain embodiments, a temperature probe 14 (tapered thermowell withtwo type thermocouples) may be inserted into an acrylate (or relatedcompound) storage tank 18 via a threaded fitting 16. The thermowellprobe 12 is of sufficient length to extend into the liquid acrylate 20(typically within 4 inches of the tank bottom) to ensure that anyexothermic reaction is detected quickly (within 30 seconds of reachingthe alarm set point temperature).

In certain embodiments, a thermocouple may be attached externallydirectly to the shell of the field application type using thermallyconductive epoxy glue, yet beneath the thermal insulation protectionlayer.

In certain embodiments, field application tanks 18 may have diametersthat range from 36″ to 40″ and ISO tanks diameters are around 86″diameter. Thus, temperature probes 14 will usually range in lengthbetween 32″ and 82″. One of the thermocouples may be connected to atemperature transmitter head 22. A second thermocouple (not shown) is aspare to be used in the event that the first one fails. This willrequire connection of the alternate thermocouple leads to thetemperature transmitters when the spare is employed. The temperaturetransmitter head 22 may send a 4-20 ma signal to the GPS unit 12.

In certain embodiments, the temperature transmitter 22 employed may bedesigned to transmit temperature data between 0° Celsius (32° F.) and50° Celsius (122° F.). The mA signal may be proportional to temperature(i.e., a 4 mA signal is sent for a 0° Celsius temperature and a 20 mAsignal is sent for a 50° Celsius temperature).

In certain embodiments, the GPS unit 12 may transmit temperature andlocation data at certain time intervals (e.g., two times per day) to asatellite that relays the data to a base station 26. This data may beprocessed and populate a database 28, and the relevant information maybe accessible via a website. The GPS unit 12 may be further programmedto instantly transmit temperature data, regardless of the last time datawas transmitted, if a pre-programmed temperature threshold is exceeded.The temperature threshold may be intended to correlate to thepolymerization reaction of the acrylate. This pre-programmed alarmthreshold is typically 100° Fahrenheit (38° C.), but may be varied asambient storage conditions dictate (e.g. summer temperatures in desertenvironments that reach 40° Celsius (104° F.) or higher may require ahigher alarm threshold).

Experiments have shown that the contents of vessels exposed to ambientoutdoor temperatures in the summer months of July and August insub-tropical climates (South Texas and Louisiana) do not exceed 90°Fahrenheit (32°−33° C.). However, the 100° F. threshold may be increasedin extreme temperature environments encountered in such places as thedeserts of the Middle East and even decreased if used in cold climateslike Alberta, Canada. In certain embodiments, the range of alarmtemperatures to be useful may include approximately between 80 and 120degrees Fahrenheit.

In certain embodiments, the GPS unit 12 and temperature transmitter 22may receive electrical power from a 12 volt sealed battery 30 that ischarged by a solar panel/charge controller combination 32. The batterymay be sized to provide 90 days of power to the GPS unit and transmitterhead in the event of solar panel failure.

Certain embodiments may further utilize a response mechanism includingan alarm and response processor 40 situated in the base station 26. Forexample, once the data from the GPS unit 12 is transmitted to the basestation 26 via satellite 24, the data may be processed at a dataprocessor collection unit 28.

In certain embodiments, the processed data may activate alarms and otherresponsive action in processor 40. In the event of a temperatureexcursion (temperature exceeding 100° F.), the GPS transceiver on thetank 12 may send a signal to the satellite that can relay the signal tothe base station 26. This base station may be programmed to sendnotifications via email or other communication means 27 to key responsepersonnel at the storage tank site (part of the response module 42).These personnel may respond in a number of ways, including accessing awebsite that details location and temperature of the acrylate vessel inquestion, contacting field personnel to investigate further, instructinglocal response personnel in emergency procedures (polymerizationmitigation procedures to employ, evacuation of nearby personnel,contacting local emergency responders, etc.) This notification systemmay be coupled to automated equipment via cell phone service to activatewater deluge systems to slow the rate of temperature increase, activatelocal audible and visual alarm systems, and inject emergency buffersolutions directly into the acrylate tank.

In certain embodiments, an automated response mechanism may activate theresponse module 42 directly via cell phone signal. Using this approach,after receiving the signal from the GPS system 12 indicating that atemperature excursion had occurred, the response processor 40 couldactivate the response module 42 via a cell phone link. The responsemodule 42 could then send signals to activate alarm controllers orsolenoid valves to initiate water deluge or emergency buffer solutioninjection as further described below.

In certain embodiments, as a result of the signal from the GPS unit 12,response module 42 may activate a chemical delivery unit having achemical supply pump 44 to introduce chemicals into the tank 18 tocontrol, stop or slow polymerization. Although the exact composition mayvary, an example of such chemical is an emergency buffer solution havingapproximately 84% acetic acid, 8% hydroquinone, and 8% anhydrous sodiumacetate. This pumped solution may be sprayed from chemical header 46within the tank 18 or injected directly into the acrylate via a dip tubethat extends into the tank. Dip tubes are generally an integralcomponent of the storage tanks and are used as a means for dischargingacrylate into the system being treated.

Alternatively, or in combination, as need be, response module 42 mayactivate a cooling solution delivery unit having a spray pump 48,whether automated or manual, to dispense cooling solution (for example,water) onto the surface of the tank 18 to reduce the externaltemperature and control the polymerization reaction of the acrylate 21within the tank 18.

In certain embodiments, alarm and response process 40 may furtherprovide visual and audible alarms to operators at the remote basestation 26 so that actions may be taken to remove the tank to a safelocation or to initiate evacuation of personnel to a safe distance awayfrom the tank 18.

In certain embodiments, a method for remotely monitoring the temperatureof acrylate in a storage tank may comprise the steps of:

providing the tank 18 with an internal temperature sensor or probe 14;

attaching the output of the probe 14 to a temperature transmitter 22powered by a battery 30 having a solar panel/charge controller 32;

transmitting temperature data from the temperature transmitter 22 to aglobal positioning receiver/transmitter 12 and determining the locationof the tank while in communication with a satellite 24;

receiving the transmitted temperature data and tank location data fromthe satellite at a remote base station 26;

processing and collecting the temperature and location data forcomparing the processed temperature data to predetermined temperatureset points 28; and

initiating alarms and responses in a response processor 40 when thetemperature data corresponds to the predetermined temperature set pointsand in appropriate environments.

In certain embodiments, further steps in the method may include:

additionally transmitting response data from the response process 40 toa response module 42 via the satellite 24 and the global positioningreceiver/transmitter 12;

providing power to the response module from a battery 31 having a solarpanel/charge controller 33; and activating a response to control apolymerization reaction of the acrylate 21 in the storage tank.

In certain embodiments, the base station may be programmed to sendnotifications via email to key response personnel who initiate and takeresponsive action through automated subsystem or manually takecorrective action.

The acrylate-based additives and compounds of the present disclosure canbe used as a sulfur scavenger in a variety of applications. Theseinclude downhole applications (e.g., drilling, fracturing, completions,oil production), use in conduits, containers, and/or other portions ofrefining applications, pipeline treatments, water disposal and/ortreatments, and sewage disposal and/or treatments.

In certain embodiments of the present disclosure, the treatment fluidsand/or additives of the present disclosure may be introduced into asubterranean formation, a well bore penetrating a subterraneanformation, tubing (e.g., a pipeline), and/or container using any methodor equipment known in the art. Introduction of the treatment fluidsand/or additives of the present disclosure may in such embodimentsinclude delivery via any of a tube, umbilical, pump, gravity, andcombinations thereof. The treatment fluids and/or additives of thepresent disclosure may, in various embodiments, be delivered downhole(e.g., into the wellbore) or into top-side flowlines/pipelines orsurface treating equipment.

For example, in certain embodiments, treatment fluids and/or additivesof the present disclosure may be applied to a subterranean formationand/or well bore using batch treatments, squeeze treatments, continuoustreatments, and/or combinations thereof. In certain embodiments, a batchtreatment may be performed in a subterranean formation by stoppingproduction from the well and pumping a specific amount or quantity of atreatment fluids or additive into a well bore, which may be performed atone or more points in time during the life of a well. In otherembodiments, a squeeze treatment may be performed by dissolvingacrylate, treatment fluids, or related additives in a suitable solventat a suitable concentration and squeezing that solvent carrying theacrylate or related compound(s) downhole into the formation, allowingproduction out of the formation to bring the acrylate or relatedcompound(s) to the desired location.

In still other embodiments, treatment fluids and/or additives of thepresent disclosure may be injected into a portion of a subterraneanformation using an annular space or capillary injection system tocontinuously introduce the treatment fluid(s) and/or additive(s) intothe formation. Other means and/or equipment that may be used tocontinuously inject treatment fluids and/or additives of the presentdisclosure into a well bore include, but are not limited to slip-streamsystems, annulus drip systems, cap strings, umbilical strings, gas liftsystems, continuous metering systems, subsurface hydraulic systems,bypass feeders, and the like.

In certain embodiments, such continuous injection equipment at a wellsite may be controlled from a remote location and/or may be partially orcompletely automated. In certain embodiments, a treatment fluidcomprising acrylate or related compounds of the present disclosure maybe circulated in the well bore using the same types of pumping systemsand equipment at the surface that are used to introduce treatment fluidsor additives into a well bore penetrating at least a portion of thesubterranean formation. In certain embodiments, acrylate or relatedcompounds of the present disclosure could be dried and formed into asolid for delivery into rat holes, tanks, and/or a wellbore.

For example, acrylate or related additives of the present disclosure maybe introduced into a well bore using a capillary injection system asshown in FIG. 4. Referring now to FIG. 4, well bore 105 has been drilledto penetrate a portion of a subterranean formation 100. A tubing 110(e.g., production tubing) has been placed in the well bore 105. Acapillary injection tube 130 is disposed in the annular space betweenthe outer surface of tubing 110 and the inner wall of well bore 105. Thecapillary injection tube 130 is connected to a side-pocket mandrel 140at a lower section of the tubing 110. Treatment fluids and/or solutionscomprising acrylate or related additives may be injected into capillaryinjection tube 130 at the wellhead 108 at the surface (e.g., using oneor more pumps (not shown)) such that it mixes with production fluid ator near the side-pocket mandrel 140. The system shown in FIG. 4 also mayinclude one or more valves (not shown) at one or more locations alongthe capillary injection tube 130, among other reasons, to preventflowback of fluid or gas to the surface through the tube. Othercapillary injection systems and side pocket mandrel devices (e.g., thoseused in gas lift production) may be used in a similar manner to thesystem shown in FIG. 4.

In certain embodiments, an additive of the present disclosure may beadded to a pipeline where one or more fluids enter the pipeline and/orat one or more other locations along the length of the pipeline. Inthese embodiments, the additive may be added in batches or injectedsubstantially continuously while the pipeline is being used.

EXAMPLES

Table 1 below shows the results of an example test of one embodiment ofthe present disclosure. In this example, 150 mL of water containing 300ppm hydrogen sulfide was adjusted to pH=8 in two sealed flasks. Onesample was used as a control test without adding anything. The other wastreated by a suitable amount of methyl acrylate solution (3%). This testwas run at 55° C. for 1 hour. After the test, the blank sample stillcontained 250 ppm H2S. The results of the one with acrylate treatmentare shown in Table 1.

TABLE 1 Results of methyl acrylate treatment at pH = 8 Time (h) H₂Sconcentration (ppm) 0 300 0.5 <20 1 0

An embodiment of the present disclosure is a method comprising:providing a treatment fluid comprising a carrier fluid and anacrylate-based additive; and introducing the treatment fluid into atleast a portion of a subterranean formation where one or more sulfurspecies are present.

Another embodiment of the present disclosure is a method comprising:providing a treatment fluid comprising a carrier fluid and anacrylate-based additive, and introducing the treatment fluid into atleast a portion of a conduit or container where one or more sulfurspecies are present.

Another embodiment of the present disclosure is a method for scavenginga sulfur species from a sulfur-containing fluid, the method comprising:providing an additive comprising an acrylate-based compound, andintroducing the acrylate-based compound into at least a portion of thesulfur-containing fluid.

Therefore, the present disclosure is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent disclosure may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified and all such variations are considered within the scope andspirit of the present disclosure. While compositions and methods aredescribed in terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods can also “consistessentially of” or “consist of” the various components and steps. Allnumbers and ranges disclosed above may vary by some amount. Whenever anumerical range with a lower limit and an upper limit is disclosed, anynumber and any included range falling within the range are specificallydisclosed. In particular, every range of values (of the form, “fromabout a to about b,” or, equivalently, “from approximately a to b,” or,equivalently, “from approximately a-b”) disclosed herein is to beunderstood to set forth every number and range encompassed within thebroader range of values. Also, the terms in the claims have their plain,ordinary meaning unless otherwise explicitly and clearly defined by thepatentee. Moreover, the indefinite articles “a” or “an”, as used in theclaims, are defined herein to mean one or more than one of the elementthat it introduces. If there is any conflict in the usages of a word orterm in this specification and one or more patent or other documentsthat may be incorporated herein by reference, the definitions that areconsistent with this specification should be adopted.

What is claimed is:
 1. A method comprising: providing a treatment fluidcomprising a carrier fluid and an acrylate-based additive, wherein theacrylate-based additive comprises at least one compound selected fromthe group consisting of compounds having the general formula:

where R₁ is a functional group selected from the group consisting of analkyl group, an alkene group, an alkyne group, an ester group, an ethergroup, and any combination thereof; and R₂ is a hydrocarbon chain;introducing the treatment fluid into at least a portion of asubterranean formation where one or more sulfur species are present; andallowing the acrylate-based additive to interact with the sulfur speciesto reduce the amount of or inactivate at least a portion of the sulfurspecies present in the subterranean formation.
 2. The method of claim 1wherein the pH level of the treatment fluid is approximately neutral. 3.The method of claim 1 wherein the pH level of the treatment fluid is atleast
 5. 4. The method of claim 1 wherein the acrylate-based additivefurther comprises one or more acrylate derivatives.
 5. The method ofclaim 4 wherein the one or more acrylate derivatives comprises anacrylate derivative containing a side chain with sulfur scavengingfunctionality.
 6. The method of claim 1 wherein the concentration of theacrylate-based additive in the treatment fluid is from about 0.5% toabout 15% by weight of the treatment fluid.
 7. The method of claim 1wherein the acrylate-based additive is provided in a closed storage tanksystem at a site where a well bore penetrating at least a portion of thesubterranean formation is located, the tank system being equipped withat least an internal temperature probe and transmitter for remotemonitoring of the temperature in the closed storage tank system.